This article is about the Viking people. There is also an article about NASA's Viking program.

Vikings were warriors from Scandinavia who in the years between 800 and 1050 colonised, raided and traded the lengths of the coasts[?] and islands of Europe and North America.
They called themself Norse.
Although they are commonly conceived of as a people bringing terror and destruction in their wake, it should be noted that many also made settlements, traded and peacefully co-existed with their neighbours.
The Viking Age is the name of the latter part of the early Iron Age in Scandinavia.

The achievements of the Vikings were quite exceptional.
For instance they made distance tables for sea voyages that were so exact that they only differ 2-4% from modern satellite measurements, even on long distances such as across the Atlantic Ocean.
They founded cities such as Jorvik (York), Kiev and Dublin.
A colonisation of America was started but was never completed.
Some also think the Vikings made it as far south as Mexico.

The Germanic word-stem vik or wik has to do with markets, and was the usual suffix to mean "market town" in the same way that burg means "fortified place".
Sandwich and Harwich in England still show this termination, and the recently excavated Frankish port town of Quentovic shows the same ending.
The Viking propensity for trade is easily seen in market ports such as Hedeby; close to the border with the Franks it was effectively a crossroads between the cultures, until its eventual destruction by the Norwegians in an internecine dispute in c. 1050.

The first report of a Viking raid dates from 793, when the monastery at Lindisfarne on the east coast of England was pillaged by foreign seafarers.
For the next 200 years, European history is filled with tales of Vikings and their plundering.
Vikings conquered most of Ireland and large parts of England, they travelled up the rivers of France and Spain, and gained control of areas in Russia and along the Baltic coast.
Stories tell of raids in the Mediterranean and as far east as the Caspian Sea.

Besides allowing the Vikings to travel far distances, their longships gave them tactical advantages in battles. They could perform very efficient hit-and-run attacks, in which they attacked fast and unexpectedly and left quickly before a counteroffensive could be launched.
Longships could also sail in shallow water, allowing the Vikings to get far inland along rivers.

A reason for the raids is believed by some to be overpopulation caused by technological advances such as the use of iron, although another cause could well be pressure caused by the Frankish expansion to the south of Scandinavia.
For people living along the coast it seems natural to seek new land by sea. Another reason is that in that period several European countries (particularly England, Wales and Ireland) were in internal disarray and easy prey; the Franks, however, had well-defended coasts and heavily fortified ports and harbours. Pure thirst for adventure may also have been a factor.

After decades of plundering, resistance in other parts of Europe became more effective and Christianity was introduced into Scandinavia, which led to milder tendencies.
In addition the kingdoms of Norway, Denmark and Sweden evolved and it is to be believed that their kings wanted more peaceful circumstances.